On 6/21/10 1:38 PM, Matthew S. Crocker wrote:
Everything is software, a 'Session Border Controller' is software. Well mostly. As an example, Acme Packet SDs have very expensive (comparatively speaking, at least) content addressable memory (CAM) wherein lives the lookup table for all active SIP sessions, thus allowing the hardware to deal with a much higher volume of RTP packets than a general purpose computer of the same general size and "power" could hope to process, not to mention making it more resilient to DoS attacks.
Just like with, say, routers, you can do wonderful things with a general purpose computer until you hit a capacity barrier, where you realize that there's yet one more reason that people send Cisco boatloads of money for high-end routers. ;-)
For 2000 subscribers I would highly recommend you partner with an existing VoIP provider and resell their service. They can handle all of the VoIP heavy lifting and send you the Call Detail Records which you can then use to bill.
He said 2,000 concurrent sessions, which is rather larger unless is town is occupied solely by call centers squeezing out every penny from their carrier. Actually, that's a suspiciously big number--maybe he meant 2,000 subscribers. I'd worry about who is going to do the customer service, not to mention what level you want to live up to, early in this process. That's likely to have more to do with customer satisfaction and consequent retention than whether you outsource your voicemail server.
If you want to do it yourself you'll probably have to live in the open source world to keep below the $50,000 limit.
If you go fully commercial, high-end, with some redundancy, you can easily blow through a million before you're ready to turn on the first customer. I quite agree with Matthew on your two basic choices. To the list of open source switches you're looking at, I'd add Freeswitch. And, yes, it can certainly be done with some of the products you've mentioned (I'm not familiar enough with some of them to have an opinion). It doesn't come with a nice SE to help you design everything at "no extra charge" like Broadworks would, but it can certainly be done. I know of one small provider who uses Asterisk and a bunch of their own software, with a staff of 3ish, one of them spending most of his time as a programmer doing his best to provide the customers with a nice experience in their custom, web-based front end. --Jon Radel